Here's the Common English Bible translation of the gospel lesson for this coming Sunday, which in the liturgical year is the day on which we celebrate "The Baptism of Our Lord" or "The Baptism of Jesus."
"John was in the wilderness calling for people to be baptized to show that they were changing their hearts and lives and wanted God to forgive their sins. Everyone in Judea and all the people of Jerusalem went out to the Jordan River and were being baptized by John as they confessed their sins. John wore clothes made of camel's hair, with a leather belt around his waist. He ate locusts and wild honey. He announced, 'One stronger that I am is coming after me. I'm not even worthy to bend over and loosen the strap of his sandals. I baptize you with water, but he will baptize you with the Holy Spirit.'
About that time, Jesus came from Nazareth of Galilee, and John baptized him in the Jordan River. While he was coming up out of the water, Jesus saw heaven splitting open and the Spirit, like a dove, coming down on him. And there was a voice from heaven: 'You are my Son, whom I dearly love; in you I find happiness.'"
In a gospel that begins with Jesus' public ministry rather than his birth, and that in all likelihood is the first gospel written, the first attempt by anyone to tell in written form "the beginning of the good news about Jesus Christ, God's Son," that this is the first story told indicates its hyper-abundance of meaning and import. Here I just hint at a few key points:
1) By being baptized by John, Jesus witnesses to the continuity between John's ministry (and the entire prophetic tradition that preceded him) and his own ministry.
2) By being baptized by John, Jesus points forward to his future ministry that continues but also transcends (without exactly replacing) the ministry of John.
3) His baptism fulfills what the prophets wrote about in Isaiah 40:3, Malachi 3:1, and Exodus 23:20. For Mark, this is the starting place.
4) Jesus' baptism sends him on a mission, first into the midst of wild animals where Satan tempts him and the angels minister to him, then straightaway into the calling of his disciples and the long journey of exorcisms, healings, teachings, and so much more that constitutes his life's work until he is crucified.
5) By being baptized for the forgiveness of sins, Jesus becomes sin, completely. Jesus repents. Given who Jesus is, the Son of God, this means God takes sin into Godself, and the nature of God (if we can say it this way), is itself repentance. This point, in the midst of all these points, should give us extreme pause for thought, humility, and repentance ourselves.
6) It's a Jesus-then, Jesus-now thing, from a literary perspective. So just as Jesus was baptized then, so too each of our individual baptisms participates now in his baptism. If this book was used in a liturgical setting (which is very likely) then it is like a remembrance of baptism litany at the beginning of worship, reminding the worshipping community of their own baptism by narrating the baptism of Jesus.
7) The baptism is like an initiation rite, initiating him into the priesthood (of Melchizedek, see Hebrews) and into the mission of his Father.
8) Jesus stands in for, in a sense is, all of humanity. His life as all of humanity begins here, in baptism.
9) Notice what the Spirit is up to in this text. Lots. It's Pentecost in the life of Jesus, which will be repeated later in the life of the church.
10) Notice what the Father says concerning his Son. It is not just initiation, it is also confirmation, affirmation, of who Jesus is as the Son of God, and what regard the Father has for who this Jesus is and what he will do and be.
And there's so much more, that doesn't even start to cover it. But that will need to wait for the sermon on Sunday.